1. Field of the Invention
Embodiments of the invention relate generally to a digital temperature detection circuit adapted for use with a semiconductor device. In particular, embodiments of the invention relate to a digital temperature detection circuit that detects an internal temperature of a semiconductor device in a digital form.
This application claims priority to Korean Patent Application No. 2006-6186, filed on Jan. 20, 2006, the subject matter of which is hereby incorporated by reference in its entirety.
2. Description of the Related Art
The internal temperature of a semiconductor device must be detected for various purposes. For example, in Dynamic Random Access Memory (DRAM), a refresh operation is required in order to accurately preserve data stored in the DRAM. The length (or period) of the refresh cycle is commonly controlled in relation to the internal temperature of the DRAM. For example, when the internal temperature of the DRAM is relatively high, current leakage from memory cells in the DRAM increases. Thus, when the internal temperature of the DRAM is relatively high, errors due to memory cell leakage can be substantially prevented by reducing the period of the refresh cycle in the DRAM. In contrast, when the internal temperature of the DRAM is relatively low, current leakage from DRAM memory cells decreases. Thus, when the internal temperature of the DRAM is relatively low, data can be stored accurately in the DRAM even when the refresh cycle has a relatively long period. Since a DRAM consumes less power when operated with a longer refresh cycle period, the accurate detection of the internal temperature of the DRAM is an important operating parameter.
Thus, contemporary semiconductor devices typically include a temperature detection circuit adapted to detect the internal temperature of the semiconductor device. The design and/or configuration of a temperature detection circuit requires the definition (e.g., pre-set) of a critical temperature. An actual internal temperature for a semiconductor device may then be compared with the pre-set critical temperature. This comparison allows the generation of a temperature detection signal. The temperature detection signal is commonly expressed as a digital value. In a so-called “digital temperature detection circuit,” 2n critical temperature values are set and output data values, each comprising “n” bits of digital data, are generated by the digital temperature detection circuit. When using a digital temperature detection circuit, the internal temperature of a semiconductor device is detected in accordance with an output data value generated by the digital temperature detection circuit.
Additionally, due to variances in process conditions associated with the fabrication of semiconductor devices, there may be definitional gaps (e.g., a lack of measurement granularity) between the critical temperatures identifiable by conventional digital temperature detection circuits. As a result, an actual temperature measured for a particular semiconductor device may be errantly expressed. Therefore, there may be considerable differences between actual internal temperatures and “measured” internal temperature indications provided by a conventional digital temperature measuring circuit. This is particularly disadvantageous when the measured internal temperatures also lack accurate, comparative critical temperature references.
Furthermore, in a conventional digital temperature detection circuit, once the output data corresponding to the detected internal temperature is generated, it is very difficult to vary corresponding offset data commonly used to adjust the output data. Therefore, there are limited applications for the conventional digital temperature detection circuit, and the conventional digital temperature detection circuit is difficult use even in those applications in which it can be used.